1661065561686 has 16 divisors (see below), whose sum is σ = 3322157073264. Its totient is φ = 553684195584.

The previous prime is 1661065561663. The next prime is 1661065561717. The reversal of 1661065561686 is 6861655601661.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192975 + ... + 1832858.

It is an arithmetic number, because the mean of its divisors is an integer number (207634817079).

Almost surely, 2^{1661065561686} is an apocalyptic number.

1661065561686 is an abundant number, since it is smaller than the sum of its proper divisors (1661091511578).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661065561686 is a wasteful number, since it uses less digits than its factorization.

1661065561686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2162495.

The product of its (nonzero) digits is 9331200, while the sum is 57.

The spelling of 1661065561686 in words is "one trillion, six hundred sixty-one billion, sixty-five million, five hundred sixty-one thousand, six hundred eighty-six".